SN 1988Z: spectro-photometric catalogue and energy estimates^★     

Itziar Aretxaga  †  S. Benetti  R. J. Terlevich  ‡  A. C. Fabian  E. Cappellaro  M. Turatto  M. Della Valle 《Monthly notices of the Royal Astronomical Society》1999,309(2):343-354

We present a spectro-photometric catalogue of the evolution of supernova 1988Z, which combines new and published observations in the radio, optical and X-ray bands, with the aim of offering a comprehensive view of the evolution of this object and deriving the total energy radiated since its discovery. The major contribution to the total radiated energy comes at optical to X-ray frequencies, with a total emission of at least 2×10⁵¹ erg (for H₀=50 km s⁻¹ Mpc⁻¹) in 8.5 yr. A model-dependent extrapolation of this value indicates that the total radiated energy may be as high as 10⁵² erg. The high value of the radiated energy supports a scenario in which most of the kinetic energy of the ejecta is thermalized and radiated in a short interaction with a dense circumstellar medium of nearly constant density. In this sense, 1988Z is not a supernova but a young and compact supernova remnant.  相似文献   

Jahn-Teller configurations in natural spinels     

V. Kuncser  U. Russo  R. Graziani  A. Della Giusta  P. Palade  M. Bulinski  G. Filoti 《Physics and Chemistry of Minerals》1999,27(2):95-102

The local configurations and related hyperfine interactions of the tetrahedrally coordinated Fe²⁺ in two natural spinels were investigated. A special fitting procedure of the Mössbauer spectra is proposed in order to cover the involved mechanisms over the whole temperature range. The behavior of the quadrupole splitting vs temperature was successfully explained in terms of the split of the electronic 3d ground state doublet under a non-cooperative Jahn-Teller effect also providing estimates of the splitting energy for each configuration.  相似文献   

The construction of ‘local’ interest in New South Wales environmental planning processes     

Hannah Della Bosca 《The Australian geographer》2019,50(1):49-68

Deliberative democracy in the form of community participation is considered a ‘key priority’ in New South Wales (NSW) environmental planning. Community participation plays an increasingly central role in state significant developments, which are often sites of contestation. Community participation processes draw upon particular factors of place-based identity, which engage with notions of procedural legitimacy in subtle and not-so-subtle ways. This paper uses a legal geography analysis to explore this link between place-based identity and the experience of procedural legitimacy. We highlight a case study in which a contested coal mining development near Lithgow, NSW was approved by the NSW Planning Assessment Commission (PAC). This analysis examines how ‘local’ justice was constructed and mobilised in specific ways by proponents and opponents alike. Spatial factors of identity manifested in distinct ways in participation processes, particularly with respect to (i) claims to legitimacy and (ii) the lived experiences of engagement in a public forum. This case study demonstrates the way in which dualistic spatial terms such as ‘outsider’ opposition and ‘local’ support can render multiple interests of both human and non-human communities invisible. In so doing we are engaging with current work on environmental justice that examines the intersection of scale, efficacy and equity in processes of environmental governance.  相似文献   

X‐ray computed tomography: Morphological and porosity characterization of giant Antarctic micrometeorites     

Zelia Dionnet  Martin D. Suttle  Andrea Longobardo  Alessandra Rotundi  Luigi Folco  Vincenzo Della Corte  Andrew King 《Meteoritics & planetary science》2020,55(7):1581-1599

Giant micrometeorites (MMs; 400–2000 µm) are exceedingly rare and scientifically valuable. Three‐dimensional nondestructive characterization by X‐ray computed tomography (X‐CT) provides information on the petrography and thus petrogenesis of MMs and serves as a guide to maximize subsequent multi‐analytical studies on such precious planetary materials. Here, we discuss the results obtained by X‐CT on 22 giant MMs and the classification based on their 3‐D density contrast images. Scoriaceous and unmelted MMs have distinct porosity ranges (10–40 vol% versus 0–25 vol%, respectively). We observe a porosity variation inside scoriaceous MMs, which allows their atmospheric entry flight history to be resolved. For the first time, spinning entry is explicitly demonstrated for four partially melted MMs. Furthermore, we are able to resolve the thermal gradient in a single particle, based on porosity variation (seen as a progressive increase in pore abundance and size with higher peak temperatures). Moreover, we explore parent body alteration through the 3‐D analysis of pores distribution, showing that shock fabrics are either absent or weakly developed in our data set. Finally, owing to the detection of pseudomorphic chondrules, we estimate that the intensively aqueously altered C1 or CI‐like material could represent 18% of the MM flux at this size fraction (400–1000 µm).  相似文献   

Geology of the Murcia Valley and Flood Plain Modifications in the Construction of the Circus Maximus,Rome, Italy     

Elena Carpentieri  Donatella de Rita  Giuseppe Della Monica 《Geoarchaeology》2015,30(6):483-494

This paper presents a morphological and hydrogeological reconstruction of the Murcia Valley at the location of the great Roman stadium Circus Maximus in Rome. We reconstruct a valley segment using ERT (electrical resistivity tomography) and geoarchaeological drilling data that identified three main layers. The basal layer, with high resistivity values and convex shapes, is correlated to alluvial gravel and lithified silt‐clay sediments. The middle layer shows low‐to‐medium resistivity values extending to concavities between the basal convex shapes. The very low resistivity values of this middle layer characterize elliptical to circular morphologies and have been ascribed to the presence of water‐saturated clay‐silt and peaty sediments. The surface layer is characterized by widespread lateral inhomogeneity interpreted as anthropogenic fill. The data indicate a pre‐Roman anastomosed alluvial plain subsequently modified by human intervention. In an effort to reclaim the valley for construction of the Circus, the Romans utilized the natural topography and created a central embankment, later becoming the Spina, by filling depressions with sand taken from adjacent bars. Our study contributes to (1) knowledge of the pre‐Roman landscape, (2) understanding anthropogenic modification of the Murcia Valley flood plain, and (3) archaeological interpretation of the monument.  相似文献